Multicast Liveness Detection

1. A method, comprising: obtaining, by an ingress component of a first packet forwarding device, a probe packet associated with a multicast packet; transmitting, from the ingress component and through an egress component of the first packet forwarding device, the probe packet to a multicast replication component of the first packet forwarding device; replicating, by the multicast replication component associated with the egress component of the first packet forwarding device, the probe packet at least two times to form multiple copies of the probe packet, wherein a first replication generates a set of first copies of the probe packet, of the multiple copies of the probe packet, that is associated with a fabric replication of the probe packet, and wherein a second replication generates a set of second copies of the probe packet, of the multiple copies of the probe packet, that is associated with local replications, of the probe packet, that is associated with each wide area network (WAN) port on a local replication list, wherein the set of second copies egress via the WAN ports associated with the first packet forwarding device; transmitting, by the first packet forwarding device to the first packet forwarding device the set of second copies of the probe packet; transmitting, by the first packet forwarding device to multiple other packet forwarding devices, the set of first copies of the probe packet; receiving, by the first packet forwarding device, the set of second copies of the probe packet, and multiple response packets, wherein each of the multiple response packets originates at a respective one of the multiple other packet forwarding devices based on a respective one of the multiple other packet forwarding devices receiving one of the set of first copies of the probe packet; and determining, based on the set of second copies of the probe packet and the multiple response packets, a status of multiple links associated with the first packet forwarding device.

2. The method of claim 1, wherein the multiple links are associated with multiple output queues, and wherein each output queue, of the multiple output queues, is associated with one of the first packet forwarding device or another packet forwarding device of the multiple other packet forwarding devices.

3. The method of claim 1, wherein receiving the set of second copies of the probe packet and the multiple response packets includes receiving the set of second copies of the probe packet and the multiple response packets via a loopback associated with the first packet forwarding device.

4. The method of claim 1, wherein a sum of the first packet forwarding device and the multiple other packet forwarding devices is equal to a first number of packet forwarding devices, wherein a sum of the set of second copies of the probe packet and the multiple response packets is equal to a second number of packets, and wherein the method further comprises initiating an alarm when the second number is less than the first number.

5. The method of claim 4, further comprising identifying at least one packet forwarding device, of the multiple other packet forwarding devices, for which a response packet was not received.

6. The method of claim 4, further comprising causing at least one packet forwarding device, of the multiple other packet forwarding devices, for which a response packet was not received to be reset.

7. A first packet forwarding device, comprising: one or more memories; and one or more processors to: obtain, by an ingress component of the first packet forwarding device, a probe packet associated with a multicast packet; transmit, from the ingress component and through an egress component of the first packet forwarding device, the probe packet to a multicast replication component of the first packet forwarding device; replicate, by the multicast replication component associated with the egress component of the first packet forwarding device, the probe packet at least two times to form multiple replicated probe packets, wherein a first replication generates a set of first copies of the multiple replicated probe packets that is associated with a fabric replication of the probe packet, and wherein second replication generates a set of second copies of the multiple replicated probe packets that is associated with a local replication, of the probe packet, that is associated with each wide area network (WAN) port on a local replication list, wherein the set of second copies egress via the WAN ports associated with the first packet forwarding device; transmit, by the first packet forwarding device to the first packet forwarding device the set of second copies of the probe packet; transmit a replicated probe packet, of the set of first copies, to each of multiple packet forwarding devices via a respective output queue; receive, in response to transmitting the set of first copies, one or more response packets; and determine, based on the set of second copies and the one or more response packets, a liveness of output queues.

8. The first packet forwarding device of claim 7, wherein the one or more processors, to receive the one or more response packets, are to receive the one or more response packets via a loopback associated with the first packet forwarding device.

9. The first packet forwarding device of claim 7, wherein the one or more processors are further to identify at least one packet forwarding device, of the multiple packet forwarding devices, for which a response packet was not received.

10. The first packet forwarding device of claim 9, wherein the one or more processors are further to cause at least one packet forwarding device, of the multiple packet forwarding devices, for which a response packet was not received to be reset.

11. The first packet forwarding device of claim 9, wherein the first packet forwarding device is associated with an application-specific integrated circuit.

12. A packet forwarding system, comprising: multiple packet forwarding devices, each packet forwarding device, of the multiple packet forwarding devices, including one or more memories and one or more processors to: obtain, by an ingress component, a probe packet associated with a multicast packet; transmit, from the ingress component and through an egress component, the probe packet to a multicast replication component; replicate, by the multicast replication component associated with the egress component the probe packet at least two times to form multiple copies of the probe packet, wherein a first replication generates a set of first copies of the multiple copies that is associated with a fabric replication of the probe packet, and wherein a second replication generates a set of second copies of the multiple copies that is associated with a local replication, of the probe packet, that is associated with each wide area network (WAN) port on a local replication list, wherein the set of second copies egress via the WAN ports; transmit, to other packet forwarding devices of the multiple packet forwarding devices, the set of first copies of the probe packet; receive multiple response packets, wherein each of the multiple response packets originates at a respective one of the other packet forwarding devices based on a respective one of the other packet forwarding devices receiving one of the set of first copies of the probe packet; and determine, based on the set of second copies of the probe packet and the multiple response packets, a reachability of multiple links associated with the multiple packet forwarding devices.

13. The packet forwarding system of claim 12, wherein the multiple links are associated with multiple output queues, and wherein each output queue, of the multiple output queues, is associated with one of the other packet forwarding devices.

14. The packet forwarding system of claim 12, wherein the one or more processors, to receive the multiple response packets, are to receive the multiple response packets via a loopback associated with the packet forwarding device.

15. The packet forwarding system of claim 12, wherein a number of the multiple packet forwarding devices is equal to a first number of packet forwarding devices, wherein a sum of the multiple response packets and one is equal to a second number of packets, and wherein the one or more processors are further to initiate an alarm when the second number is less than the first number.

16. The packet forwarding system of claim 15, wherein the one or more processors are further to at least one of: identify at least one packet forwarding device, of the other packet forwarding devices, for which a response packet was not received, or cause at least one packet forwarding device, of the other packet forwarding devices, for which a response packet was not received to be reset.